Portion of a barbecue



FIG. 1 is an isometric view of a portion of a barbecue showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a side elevation view thereof.

The details shown in broken lines form no part of the claimed design. 

The ornamental design for a “portion of a barbecue,” as shown and described. 